The smooth muscle of the urinary bladder and large bowel is controlled by the sympathetic and parasympathetic division of the autonomic nervous system. In the present project we are examining the central autonomic mechanisms involved in this control. We are particularly interested in determining the importance of recurrent inhibition and supraspinal reflexes in these mechanisms. Electrophysiological and microelectrophoretic techniques are being employed to examine the actions and possible physiological rele of the biogenic amines, noradrenaline, 5-hydroxytryptamine and acetylcholine in these central autonomic pathways.